Recent developments in tissue culture techniques have been allowing commercial production of a variety of plants in a large scale. Particularly, in ornamental plants, the unit price of them is relatively high and therefore, propagation by means of tissue culture techniques is becoming a practical method, In plants of low price such as vegetables, on the other hand, commercial application of tissue culture techniques has not been accomplished yet due to low propagation efficiency,
Propagation techniques using a tissue culture include propagation by cutting without callus formation; formation of adventitious shoots from a culture via callus formation or without callus formation, followed by rooting to produce plants; formation of somatic embryo from a callus to produce plants; formation of shoot primordium, and the like.
As an example of propagation by cutting, there has been known to propagate shoots of asparagus by culturing small lateral branches or nodes as an explant, followed by rooting to produce plants (Chee-kok Chin, HortScience 7(4): 590-591, 1982; Takayama S. et al., Japanese Patent Application Laid-Open-to-Public Publication No. 09722/1988). There has also been reported a method of propagation by cutting a plant derived from apical meristem culture of garlic on:a propagation medium (Bhojwani S., ScientiaiHorticulturae 13:47-52, 1980). Similar method has been reported about onion (Hussey G., Sci. Hortic., 9: 227-226, 1978). Furthermore, there have been many reports on other plants, for example, caladium (Hartman R. D., Phytopathology 64(2): 237-240, 1971), cordyline (Kunisaki J. T., HortScience 10 (6): 601-602, 1975), pineapple (Mathews V. H. et al., Scientia Hort. 11: 319-328. 1979), carnation (Fujino M. et al., Summary of Lectures at 1971 Spring Meeting of Japan Society of Horticulture, p 302-303), etc.
As examples of propagation via adventitious shoot formation, African violet, common gloxinia and the like may be mentioned (Start N. D. et al., HortScience 11 (3): 204-205, 1976; Haramaki C. , Int. Plant Prop. Soc. 21: 442-448, 1971). In these plants, plantlets are obtained by cutting the adventitious shoots, followed by rooting. Relating to the propagation via formation of a callus, there are many reports on plants such as strawberry (Osawa K. et al., The Bulletin of the Vegetable and Ornamental Crops Research Station, Ministry of Agriculture, Forestry and Fisheries, Series A, 1: 41-57, 1974) and tomato (Delanghe E. et al., Scientia Horticulturae, 4:221-227, 976).
As examples of somatic embryo formation, carrot (Kamata H., Chemical Regulation of Plants, Vol. 15 (2): 62-78, 1980), garlic (Abo El-Nil M., Plant Science Letters, 9: 259-264, 1977; Araki H. et al., Summary of Lectures at the 1988 Autumn Meeting of Japan Society of Horticulture, p.254-255), asparagus(Koumura H. et al., Summary of Lectures at the 1988 Spring Meeting of Japan Society of Horticulture, p.232-233; Hirata Y. et al., ibid., p. 230-231), and the like may be mentioned.
Above described methods of propagation are set forth for exemplary purpose. For reviews of propagation techniques using tissue culture, see Furukawa J., in "Schematic Diagramm: Textbook of Tissue Culture", Seibundo Shinkosha, 1985, Kako S., in "The Culture of Organs and Tissues of Horticulture Plants"0 Seibundo Shinkosha etc.